test_app.css

* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}
body {
  height: 100vh;
  background-color: #252525;
  color: #ebebeb;
  font-family: sans-serif;
}
.container {
  width: 95%;
  margin: auto;
  margin-top: 60px;
}
h1,
h2,
h3,
h4 {
  font-family: Courier New;
  background-color: #fff44f;
  color: black;
  width: 250px;
}

.nav-bar {
  display: flex;
  background-color: black;
  width: 100%;
  align-items: center;
  position: fixed;
  top: 0;
  z-index: 10;
  overflow: hidden;
}
.nav-bar a {
  font-family: Courier;

  color: #fff44f;
  padding: 14px 20px;
  text-align: center;
  text-decoration: none;
  padding-right: 30px;
  margin-right: 80px;
}
.active {
  background-color: #252525;
  color: #ffef00;
}

.nav-bar a:hover {
  background-color: #252525;
  color: #ffef00;
  box-shadow: 0 0 15px white;
}
.main {
  text-align: center;
}
.content1 {
  display: flex;
  flex-wrap: wrap;
  padding: 20px;
  text-align: center;
}
.content1 h2 {
  background-color: #fff44f;
  color: black;
}
.side1 {
  flex: 1;
  padding: 20px;
  margin: 10px;
  height: 250px;
  width: 250px;
}

.main1 {
  flex: 1;
  padding: 20px;
  height: 500px;
  margin: 10px;
}
.main2 {
  flex: 1.6;
  padding: 20px;
  margin: 10px;
}
#video {
  text-align: center;
}

@media (max-width: 768px) {
  .content1 {
    flex-direction: column;
  }
  #video {
    position: relative;
    width: 100%;
    height: 0;
    padding-bottom: 50%;
  }
  #video iframe {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
  }
}
.heading {
  text-align: center;
}
.heading h2 {
  display: inline-block;
}
.footer {
  color: #fff44f;
  background-color: black;
  text-align: center;
  width: 100%;
  bottom: 0;
  margin-top: 40px;
  margin-bottom: 3px;
}